I like trains. I like the overground variety more than the underground one. This is simply because most times I have been on a underground train has been in London. Ever wondered what a sardine feels like when it is in a tin? Just travel on the tube. Overground trains on the other hand are most likely to be spacious and you get a reserved seat.
But the main reason I like trains is due to the fact you know where to get off, on a bus you do not.